MOPAG-projektet

SummaryPyrite is an often found mineral in many groundwater aquifers. It is well known that pyrite may oxidise rapidly in aerobic sediments by both abiotic and microbial catalysed processes. Pyrite may also be oxidised in anaerobic sediments by processes linked to reduction of nitrate. Little is known, however, about anaerobic pyrite oxidation rates and the role of microorganisms, in particular to the field scale relevant for groundwater modelling. The process is important, because it has a significant impact on the capacity of sediments to reduce the concentration of nitrate leaching to aquifers from agriculture.

The project’s purpose is to determine if anaerobic pyrite oxidation in aquifers is a microbial catalysed process. This has not been proven yet, although our preliminary results indicate that microorganisms are involved in the process. We also aim to characterise and isolate the microorganisms involved. Furthermore, the geographical distribution of the process will be studied and it will be determined if there is a relation between soil geology/geochemistry and rates of anaerobic pyrite oxidation. At one selected field site anaerobic pyrite oxidation will be studied in details. At this site transport of nitrate will be modelled to evaluate the importance of anaerobic pyrite oxidation for the capacity of the soil to reduce nitrate.

The project is highly interdisciplinary as it depends on several core disciplines: Groundwater microbiology, geomicrobiology, geochemistry, geology, and mathematical modelling. The partners of the project are GEUS (prof. Jens Aamand, senior researcher Ole Stig Jacobsen and consultant Dieke Postma), section of geography, University of Copenhagen (prof. Bo Elberling), Geological Institute, University of Aarhus (Associate prof. Steen Christensen) and the new Center for Geomicrobiology, University of Aarhus (prof. Bo Barker Jørgensen).